1. Field of the Invention
The invention relates to protective devices for doorways and in particular to a device adapted to be manually installed on the inside of the protected door to prevent unauthorized opening of the protected door, and to actuate an alarm when an unauthorized opening of the door is attempted.
2. Description of the Prior Art
Numerous styles and types of door locks have been constructed using rigid locking bars or bolts to provide extra security at night for residents of a dwelling. Most of these known lock constructions are permanently mounted on the door and door frame, which imparts a cluttered, unsightly appearance to the door since such a device is usually in addition to the existing door lock.
In most of these known locking devices which use retaining bars or bolts, the bolt extends horizontally between the door and frame across the swinging edge of the door. Due to the limited material thickness of the door and door frame, such devices can be broken out if sufficient force is applied to the door. Also, these prior devices are difficult to install in that they require internal drilling of the door as well as of the frame, such as for the usual "dead-bolt" type of lock construction. Also, such dead-bolt mechanism and associated latch plate must be bolted or screwed on both the door and frame.
It is desirable that some type of locking device be provided which is not a permanent part of the door or frame and which can be easily installed by the user when extra protection is required. Also, such device should be extremely difficult to forcibly break away from the door and door frame and one which will not present an unsightly appearance when not in use. Also, such a lock device should be of a relatively inexpensive construction, and one which can be installed with a minimum of labor and expense.
Many of these problems have been eliminated by my prior door lock construction shown and described in U.S. Pat. No. 4,235,464. Although my prior door lock eliminates many of these problems, it is desirable that, in addition to physically preventing entry through the door, some type of an alarm be provided to further deter forcible entry and also to indicate to the occupants that an intruder is attempting to open the protected door.
Numerous alarm devices have been devised and constructed over the years for mounting on a door or adjacent thereto for sounding an alarm when the door is opened to protect the occupants of a dwelling. Examples of such prior art alarms are shown in U.S. Pat. Nos. 1,099,777, 1,377,939, 2,824,300, 3,121,864, 3,261,010, 3,270,333, 3,378,830, 3,768,086, 3,798,627, 3,878,539, and 4,059,832. Many of these prior devices appear to provide a satisfactory alarm and are suitable for their intended purpose. However, such prior alarms only give an audible signal that the door is being opened and do not provide any means of physically impeding the opening of the door. Also, many of these prior alarms do not remain activated if the door is immediately closed by an intruder once the alarm is initially sounded.
Therefore, it is desirable that some type of security device be provided that is not a permanent part of the door or frame, which can be easily installed by the user when extra protection is required, which is extremely difficult to forcibly break away from the door and door frame, which will not present an unsightly appearance when not in use, which is of a relatively inexpensive construction, and which can be installed with a minimum of labor and expense, and which provides an alarm when the protected door is attempted to be opened, which alarm will not deenergize if the intruder immediately recloses the door. My improved combination door lock and alarm, which is described below and shown in the drawings, is believed to satisfy these requirements and provide these advantages.